The present invention relates to a method and apparatus for temporarily increasing the absorptance of optical transmitting components, such as lenses and filters.
Optical transmitting components of variable absorptance are used in many fields of optics. One known example is eyeglass lenses which are to serve temporarily also as sunglasses. So-called phototropic glasses are known for this purpose; they become darker in bright sunlight due to the ultraviolet content thereof and thereby protect the eye from excessive or unpleasant brightness. These phototrophic glasses, however, have the disadvantage that their change in absorptance takes place too slowly and that they function inadequately behind the windshields of automobiles.
Optical transmitting components of temporarily variable absorptance are furthermore advantageous for numerous optical instruments. Thus, for example, it is frequently necessary temporarily to weaken a light ray to a predetermined extent. For this, so-called gray or neutral filters are used; they are generally moved by mechanical means into and out of the path of the ray. But use of such mechanical means has the disadvantage that automating is expensive and is disturbance-prone, due to the involved mechanical motion of involved parts.